Radio frames in a Long Term Evolution (LTE) system and an LTE-Advanced (LTE-A) system include frame structures with a Frequency Division Duplex (FDD) mode and a Time Division Duplex (TDD) mode. FIG. 1 is a diagram of a frame structure in the existing LTE/LTE-A FDD system. As shown in FIG. 1, one radio frame with the length of 10 ms consists of twenty time slots each being 0.5 ms in length and numbered from 0 to 19; the time slots 2i and 2i+1 form a subframe-i with the length of 1 ms. FIG. 2 is a diagram of a frame structure in the existing LTE/LTE-A TDD system; one radio frame with the length of 10 ms consists of two half frames each with the lengths of 5 ms; each half frame includes 5 subframes with the length of 1 ms; the subframe-i is defined as two time slots 2i and 2i+1 each with the length of 0.5 ms.
In the above two types of frame structures, for a Normal Cyclic Prefix (NCP), one time slot includes 7 symbols with the length of 66.7 microseconds (us), in which the CP length of the first symbol is 5.21 us, and the CP length of the other 6 symbols is 4.69 us; for an Extended Cyclic Prefix (Extended CP), one time slot includes 6 symbols, and the CP length of all the symbols is 16.67 us. Supported uplink and downlink configuration is as shown in Table 1:
TABLE 1Downlink-uplinkUplink-conversiondownlinkpointSubframe numberconfigurationperiod012345678905 msDSUUUDSUUU15 msDSUUDDSUUD25 msDSUDDDSUDD310 ms DSUUUDDDDD410 ms DSUUDDDDDD510 ms DSUDDDDDDD65 msDSUUUDSUUD
For each subframe in one radio frame, “D” represents a subframe for downlink transmission; “U” represents a subframe for uplink transmission; “S” represents a special subframe, which includes three parts, a Downlink Pilot Time Slot (DwPTS), a Guard Period (GP) and an Uplink Pilot Time Slot (UpPTS).
In the LTE system, a Hybrid Automatic Repeat reQuest (HARQ) progress refers to: when a transmitting end has data to be transmitted, a receiving end allocates information, such as time-frequency resource and packet information, which is required for transmission for the transmitting end through a downlink signalling. The transmitting end transmits data according to these pieces of information, and saves the data into its own buffer to facilitate retransmission. The receiving end performs detection after receiving the data, and if the data are correctly received, the receiving end transmits an Acknowledgment (ACK) to the transmitting end; after receiving the ACK, the transmitting end clears a buffering memory used in this transmission, and ends this transmission. If the data are not correctly received, the receiving end transmits a Non-acknowledgment (NACK) to the transmitting end, and saves a wrongly received packet into a buffer of the receiving end; after receiving the NACK information, the transmitting end extracts the data from its own buffer, and performs retransmission with a specific packet format in a corresponding subframe and at a corresponding frequency domain position. After receiving the retransmitted packet, the receiving end combines the retransmitted packet with the wrongly received packet, and performs detection again. The process above is repeated until the data are correctly received or the number of transmission times exceeds a maximum threshold of the number of transmission times.
In the LTE/LTE-A system, there are provisions below on scheduling and timing of a Physical Downlink Shared CHannel (PDSCH) in the downlink HARQ, that is, there are provisions below on the scheduling of the downlink HARQ: User Equipment (UE) detects a Physical Downlink Control CHannel (PDCCH) on the subframe n, and analyzes the PDSCH of the current subframe according to information of the PDCCH.
In the LTE/LTE-A FDD system, there is a timing rule below on a Physical Uplink Control CHannel) corresponding to the HARQ-ACK for the sent PDSCH in the downlink HARQ, that is, there is a rule below on a timing of the downlink HARQ: the UE detects the PDSCH transmission or instructs the PDCCH of a downlink SPS release on the subframe n, and transmits a corresponding HARQ-ACK on the subframe n+4. In the LTE/LTE-A TDD system, there is a rule below on the timing of the downlink HARQ: the UE detects the PDSCH transmission or instructs the PDCCH of the downlink SPS release on the subframe n-k, and transmits a corresponding HARQ-ACK on the uplink subframe n, wherein k belongs to K. Table 2 includes values of K in different uplink and downlink configurations. The values of K are as shown in Table 2:
TABLE 2Uplink-downlinkSubframe number nconfiguration01234567890——6—4——6—41——7, 64———7, 64—2——8, 7,————8, 7,——4, 64, 63——7, 6,6, 55, 4—————114——12,6, 5,——————8, 7,4, 7115——13,———————12,9, 8,7, 5,4, 11, 66——775——77—
In the LTE FDD system, the uplink subframes and the downlink subframes are in one-to-one correspondence. Thus, when the PDSCH includes only one transmission block, the UE will feed back ACK/NACK information of 1 bit; when the PDSCH includes two transmission blocks, the UE will feed back ACK/NACK information of 2 bits; the UE adopts PUCCH format 1a/1b to transmit the ACK/NACK information of 1/2bits. In the TDD, the uplink subframes and the downlink subframes are not in one-to-one correspondence, that is, the ACK/NACK information corresponding to a plurality of downlink subframes needs to be transmitted on the PUCCH channel of one uplink subframe, wherein the downlink subframes corresponding to the uplink subframe are gathered to form a “bundling window”. There are two solutions for transmitting the ACK/NACK information. One solution is a bundling method, and the core idea of the solution is to perform logic and operation on the ACK/NACK information corresponding to the transmission blocks for the respective downlink subframes which needs to be fed back on the uplink subframe. If one downlink subframe has 2 transmission blocks, the UE will feed back ACK/NACK information of 2 bits; if each subframe has only one transmission block, the UE will feed back ACK/NACK information of 1 bit; the UE adopts PUCCH format 1 a/1 b to transmit the ACK/NACK message of 1/2bits. Another solution is a multiplexing with channel selection method, and the core idea of the solution is to adopt different PUCCH channels and different modulation symbols on the PUCCH channels to express different feedback states of the downlink subframes needing to be fed back on the uplink subframe. If a downlink subframe has a plurality of transmission blocks, the ACK/NACK corresponding to the multiple transmission blocks of the downlink subframe is subjected to logic AND (spatial bundling), and then subjected to channel selection; the UE adopts format 1 b with channel selection to transmit the ACK/NACK message.
Relative to the LTE system, the LTE-A system has a most outstanding characteristic that a carrier aggregation technology is introduced into the LTE-A system, that is, the bandwidth of the LTE system is aggregated to obtain a larger bandwidth. In the system with carrier aggregation, a carrier for aggregation is either called a Component Carrier (CC) or a Serving Cell (SC). In addition, concepts of a Primary Component Carrier/Cell (PCC/PCell) and a Secondary Component Carrier/Cell (SCC/SCell) are further provided. The system in which carrier aggregation is performed at least includes a primary serving cell and a secondary serving cell, in which the primary serving cell is always in an activated state, and it is specified that the PUCCH is only transmitted on the Pcell.
Under the LTE-A carrier aggregation system, when the HARQ-ACK message is transmitted on the PUCCH, two transmitting modes are defined: PUCCH format 1b with channel selection, and PUCCH format 3. For the UE with a plurality of serving cells, if the UE can only support the aggregation of 2 serving cells at most, then when there are multiple serving cells configured for the UE, the UE will adopt the PUCCH format 1b with channel selection mode to transmit the HARQ-ACK. If the UE can support the aggregation of more than 2 serving cells, then when there are multiple serving cells configured for the UE, a base station will further adopt a high signalling to configure whether the UE adopts the PUCCH format 1b with channel selection mode or the PUCCH format 3 to transmit the HARQ-ACK response information.
The inventor of the disclosure has found at least the following technical problems in the existing technology in the process of implementing the technical solutions of the embodiments of the disclosure:
In the subsequent version, a dual connectivity technology is introduced, that is, the uplink control information is transmitted under the condition that the backhaul among a plurality of aggregated/collaborated serving cells is in a non-ideal state, so the existing technique in which the PUCCH is transmitted only on the Pcell is not situtable, and there is no effective solution at present.